When I disable W3TC, it works again. Only Post-Tiles breaks (out of my 20-odd plugins) with W3TC.
Have enabled most of the cache, CSS/JS related optimizations (as suggested by YSLOW) in W3TC -- I cannot do away with W3TC - and would like to have Post Tiles too.
PS: Let me know what information I can provide to help resolve this issue.
;-p r a b u!